Field of the Invention
The present invention relates to carders, in which a thin layer of fibrous material is processed by a series of carding surfaces, which are provided with coverings with tips, and are set in motion relative to one another, in which the flock fibres are opened, in order to produce separated, stretched fibre strips. In this operation, the impurities and dirt are eliminated, the fibres are mixed with one another, and a fibre strip with a regular yarn count is obtained, which is collected in large containers, to be sent to the successive processing stages.
In particular, the subject of the present invention is the operation of packing in the collection container, the strip produced by a carding unit, or by a drawing frame.
In the known art, devices are described for collection of the strip produced by a carder, for example in the German patent in the name of Rieter, no. 1,510,339, and in the Italian patent application MI95A02123 in the name of the same applicant. In these devices, the exchange of the strip end, when the full container is replaced by an empty container, with corresponding gripping and cutting of the strip section to be joined, is complex and unreliable; inter alia it takes place with both containers at a standstill.
In order to make apparent the technical problems which are involved in this operation, and to eliminate them by means of the present invention, the assembly of the carding unit and the collection unit are described briefly with reference to the drawing in FIG. 1. In the carding unit 1, the fibres, which are separated and mixed in the carding operation, are matted into a web, which has a consistency which is sufficient to be drawn through a condenser by a calender unit 2, which is also known as the drawing unit. This strip is supplied to the collection unit 3, which draws it by means of two calenders (not shown in the figure), from the carding unit, and packs it in the containers 4, by means of a rotary distributor plate, which places the strip in the container itself, in superimposed coils. This rotary distributor 5 is eccentric relative to the container 4 being filled, which is disposed beneath the collection unit 3.
The distributor 5 consists of a horizontal plate, which is driven with rotary motion around its own centre, according to the arrow B, at a speed of approximately hundreds of revolutions per minute.
In turn, the underlying container 4, which is being filled, has a cylindrical shape, and is disposed coaxially on a rotary platform 6, which in turn is driven with rotary motion around its own vertical axis according to the arrow C, at a speed of approximately tens of revolutions per minute, thus distributing the strip in the container, according to coils, the centre of which is translated according to coaxial circles, relative to the platform 6 and the container 4 which is being filled, with an accumulation which increases progressively in thickness but not in level, owing to the effect of the progressive compression of the spring which is beneath the base of the container 4.
The collection of the strip in containers, so that it can be sent to the subsequent processing operations, makes the carding operations independent from the subsequent operations.
At the output of the calenders 2 of the carder 1, along the path of the strip 7 according to the arrow A, towards the collection unit 3, and in particular at the guide pulleys 8a,b,c of the latter, according to the known art there is provided a thread-sensor device, which detects whether the strip is present or absent, i.e. whether it is continuous or broken, and in the latter case, the device stops the carder/collection assembly.
The strip which is produced during the carding has limited tensile strength, and must be suitably processed: for this purpose, packing the strip in a container, in superimposed coils, allows it to be extracted subsequently, without generating tensions which the limited strength of the strip cannot withstand. It is also known from the state of the art, for example from patent application MI95A02123 in the name of the same applicant, that for this reason the container for collection of the strip is provided with a mobile base 9, which is thrust upwards by a spring 10, or by an equivalent element, which allows the base 9 to descend as the depositing of the coils of strip onto its surface progresses; this depositing compresses the spring 10, with a range which is limited by an upper end-of-travel projection for the plate 9, and a lower support projection for the spring 10. By this means, the free section of strip, from the distributor element, to the level at which it is deposited in the depositing operation, as well as from the collection element, to the level from which it is collected in the successive operation, in which the strip in the container is supplied to a successive processing operation, remains quite short, and an effect of undesirable drawing of the strip is substantially prevented.
The present invention relates more specifically to the operation of replacement of the containers, and to control and transfer of the end of the strip, from the full container to the empty container, which replaces it in sequence.
According to the known art, this operation is commonly carried out manually by the operators, who, when the pre-determined length required for filling of the container 4 has been reached, replace the full container by the new container, beneath the rotary distribution unit, and cut off the strip deposited in the full container, placing the end on the base of the new container. The mobile base 9 of the container is usually provided with needles or projections to engage and hold the end, and thus to start the new depositing of coils in the new container.
In the aforementioned patent application in the name of the same applicant, there is described a recent automatic container-changing device, in which, however, changing the container makes it necessary to change the speed of the machine, and to slow down or stop production of the machine for the change, with two transitory speeds at the beginning and end of the operation.
These methods for changing and moving the container are not altogether satisfactory, particularly in high-productivity carding units, which process 200 to 400 m of strip per minute.